Bruker and Berkeley Lab Combine NMR with SAXS for Analyzing Large Protein Complexes

Bruker and Lawrence Berkeley National Laboratory are collaborating to develop structural biology methods and tools that integrate small-angle x-ray scattering (SAXS) technology with nuclear magnetic resonance (NMR). The aim is to generate a set of data analysis algorithms for determining the structures of larger, multidomain proteins and protein complexes with DNA, RNA, or other proteins.

The organizations claim that combining the NMR-derived 3-D atomic structure of protein domains with calculations of overall size, shape, and envelope constrains provided by SAXS will enable more accurate analysis under near-native solution conditions.

The organizations point out that while one of the benefits of NMR is that the technology can be used to study proteins in solution—providing information on different regions and domains, protein flexibility, partial folding, and unstructured regions—it can only work with molecules of up to 50–70 kDa. Moreover, they continue, even with the most advanced techniques and associated hardware and probes, solution NMR often lacks the ability to determine the exact global structure of larger molecular assemblies or multidomain proteins.

Combining NMR data will SAXS is expected to compensate incomplete NMR datasets of biological molecules. Previous studies have already shown that SAXS can effectively improve the quality and accuracy of NMR structures and also potentially extend the capability of NMR to larger molecules, Bruker and the Berkeley Lab state. In addition, SAXS represents a relatively fast, economical, and straightforward technique that doesn’t require complicated sample preparation and uses only a few micrograms of unlabeled, native protein in a monodisperse solution.